The way I learnt the japanese alphabet was actually by making a phone keyboard layout and printing it off, I didn't know it was alphabetical order but yeah it makes sense
The order starts from centre, then goes left, and clockwise around, and then to the next group to the right (and down) e.g. a-i-u-e-o ka-ki-kuk-ke-ko sa-shi-su-se-so ta-tchi-tsu-te-to etc.